Network interface devices provide a demarcation point between network wiring, normally owned by a telephone company, to a subscriber's wiring at a subscriber's premises. A network interface device also usually contains a test jack so that a device known to be operational, such as a telephone, may be plugged into the test jack for connection to the network wiring. If a dial tone is received, it is thereby determined that the network wiring is operational, so a fault must be located in the subscriber's wiring. On the other hand, if no dial tone is received, the fault lies between the telephone company's central office and the network interface device.
Although network interface devices have been shown to be very reliable, an area found to be relatively susceptible to failure is the electrical interface associated with the plug and jack area. A plug is inserted into the test jack during normal operation. Therefore, it was found to be desirable to remove the test jack from the electrical circuit except during the time the test jack was actually being used to test an operating telephone. U.S. Pat. No. 4,562,311, issued to Dola, describes a telephone network interface device having a sliding cover which covers the test jack and the remainder of the network interface device, including the subscriber's wiring terminals. The sliding cover has mating metal terminals to selectively connect the network wiring to subscriber wiring when the door is closed and to the test jack when the door is slid open.
It is believed that the mechanical switch having sliding metal connections could be improved by the use of more modern switches. Furthermore, Dola's device does not allow telephone company employees to test the set of subscriber terminals, which are covered when Dola's cover is closed and disconnected when the cover is open.
Therefore, it is believed that the state of the art would be improved by a modernized device which would accomplish Dola's purpose, but by using a better switch and without obstructing access to the entire network interface device.